In trying to solve a problem, I discovered the
--session-command argument to
su, as documented here. I tried to use it on my Ubuntu 12.04 system at work, but got an 'unrecognized option' error. Sure enough, it doesn't even show up on the man page for
The linked manpage does say
--session-command is 'discouraged' but doesn't say why.
Out of curiosity, I connected to a CentOS 6.2. server at my work, and
--session-command is recognized.
Further research led me to discover that the
su used by Ubuntu comes from the
login package, whereas in CentOS it comes from
coreutils. Ubuntu also has a
coreutils package installed by default, but it doesn't contain the FSF's standard
su implementation. A detailed comparison shows that
coreutils from both distros contain 105 executable files, but there are several differences (most of which seem to just be the installed location of the files).
My question: Is
--session-command left out of Ubuntu's (or Debian's) superuser command by design, or has Ubuntu's divergent implementation simply not caught up with FSF? If by design, what is the reasoning for the omission? Related question: Why not use all the FSF's GNU Utils, anyway?
I'm sure this is documented somewhere but google was not forthcoming, given my search criteria.